Guide elements for the passage of pipes, cables or the like through walls are known. In the marine field such elements are used for passing, and possibly sealingly, ducts or cables through bulkheads, for example, pipes supplying oil within a circuit for controlling a steering cylinder.
Ships steer by means of a pump driven by a wheel, a steering wheel or the like. The pump may have reversible delivery and return, which are connected to opposing inputs of a double-effect cylinder through an oil-pressure circuit composed of a pair of supply pipes. The cylinder body translates along a stationary stem as the wheel is rotated, in one direction or the other, and a depression on one branch and an overpressure on the other branch of the circuit connecting the pump to the cylinder is generated alternatively according to the direction, in which the wheel is rotated. Therefore, ship steering can be controlled by coupling the cylinder directly to the motor or motors for outboard motors, or to the rudder for inboard motors.
Pipes of the supply circuit are configured to withstand pressure and pass from the area of the stern board where the motor or rudder is coupled, toward an intermediate area of the ship where a control station that includes pump and wheel is provided. To achieve such passage, the pipes have to move through one or more bulkheads, which need to remain under watertight conditions if so required. Moreover, since pipes end at the cylinder, which is movable, such sealing effect has to be guaranteed not only as required, in spite of the movement of the pipes, but above all to prevent the pipes from becoming bent and kinked.
In particular, the pipes are dynamically urged by the cylinder moving along the stem in alternating directions, causing the pipes to be compressed or pulled depending on the direction of translation and, therefore, on the steering direction. A bulkhead is a constraint to the movement of the pipes, which may become kinked by being bent due to the stress. Because these types of pipes are typically, made of soft metal materials such as copper, these materials may cause the pipes to become stuck or break if bent without a suitable guide, stopping or reducing the flow of oil and leading to a consequent malfunction of the steering circuit.
In an attempt to overcome this problem, tight fairleads have been introduced, where an elastic guide is placed between the pipe and the opening in the wall being, to which it is attached by a circular concentric flange. These fairleads partially solve the problem caused by the kinking of supply pipes, but also are quite cumbersome and can be used with more than one pipe only by suitably spacing passage openings in the wall. In the specific case of a steering circuit, this requires the installation of the two oil supply pipes to be significantly spaced apart, leading to larger overall dimensions or to a spreading of the pipes near the bulkhead to be traversed, thereby facilitating kinking during installation. There is a need to resolve this problem, because it is often impossible to have steering systems of ships mounted by suitably skilled and attentive personnel. This problem is particularly acute for small ships, such as rubber boats, which are often assembled by the final user using specific do-it-yourself kits.
Moreover, bulkhead feed-throughs in the prior art have fixed diameters corresponding to the diameter of the pipe to be installed. There is often a need to mount pipes having variable diameters, particularly at the end portions, for example for housing an anti-kink sleeve and a pressure-tight fastening terminal coupled to the cylinder. Therefore, peripheral tools often have to be mounted after assembling a bulkhead feed-through, while it would be desirable to assemble a bulkhead feed-through also with partially connected pipes if the opening or openings of the bulkhead allowed a pass-through of such parts of greater overall dimensions.